What Is Coral Gardening?

Gardens aren't just for backyards. Learn how the rising practice of underwater gardening helps to address coral reef depletion.

Coral Garden

A person takes care of cultured corals at the Coral Biome sea farm on July 28, 2015 in Marseille, southern France. Coral Biome is a marine biologist and aquaculturist company proposing cultured corals to researchers, hobbyists and public aquariums.

Coral gardening, a fast-growing new aquatic venture, is far more than just growing pretty creatures in a home aquarium – it is vitally important to millions of people around the world.

Corals are tiny animals called polyps that live in colonies and whose hard skeletons create large reefs teeming with aquatic life. They catch small fish and plankton. Coral reefs provide important habitats for marine life, including a large percentage of saltwater fish caught for human consumption. They are also crucial to local economies where fishing and tourism are the main sources of employment.

Big Problems Underwater

These delicate underwater systems are fragile and in danger worldwide from losses due to diseases, hurricanes, predatory starfish, overdevelopment along coastlines, and overfishing which both damages coral physically and depletes the fish that eat seaweed which can overrun coral reefs. There is also a growing demand for coral by aquarium hobbyists and for making jewelry.

On a larger scale, significant coral reef decline has been increasingly caused by climate changes in which sea levels and temperatures are rising too rapidly for coral to adapt. At the same time, more and more industrial carbon dioxide in the atmosphere is being absorbed into the ocean, making the water more acidic and dealing a serious blow to coral skeletons which are made of calcium carbonate that dissolves in acidic water. Researchers think that, taken together, these changes are causing huge swaths of coral to bleach and die; some estimates are that about a quarter of the world’s coral reefs are damaged beyond repair, with over half of the rest under serious threat.

Underwater Gardeners to the Rescue!

However, there is a growing movement to restore damaged reefs through coral gardening, known in the industry as coral aquaculture, which is showing great promise in rebuilding damaged or dying reefs - or even starting new ones in more suitable places.

While a lot of people are doing what they can to reduce damage to existing coral reefs, coral gardening is an active restoration. It is essentially like growing garden plants from cuttings, except the small bits and branches of coral are collected and grown for a few months up to two years to maturity in floating saltwater “nurseries” where they get the right amount of sunlight, and are then attached onto specially constructed submerged artificial reefs in new locations.

These reefs, made of metal, concrete, ceramic, or other seaworthy material, are placed at various depths for different corals. They are designed with the right kind of rough surfaces, holes, fissures, and “arms” to allow coral to attach quickly and get the right kind of water flow to encourage fast growth. Many artificial reefs are simple metal and wire mesh platforms; one interesting kind is a hollow “reef ball” that is anywhere from a foot to over eight feet in diameter, made of pH neutralized concrete and with various size holes to help coral, algae, sponges, and even oysters get started faster with more natural conditions.

Coral gardening is being done worldwide by local people, both volunteers and those doing it for extra income, who live close to the endangered reefs. It is also practiced on an increasing scale by commercial businesses that grow various corals sustainably for large aquariums or home hobbyists; this is an important approach that reduces the over-harvesting of corals.

Working together with public education and community training, researchers, local fishermen, and even tourism groups that encourage visiting divers to volunteer as gardeners, this new technology propagates coral sustainably, and is being used to restore seriously damaged reefs or create new man-made aquatic wonderlands.

Through coral gardening, vitally important coral reefs, crucial for millions of people as well as ocean life and all that entails, are now being protected and restored.